# uncompyle6 version 3.2.3
# Python bytecode 3.6 (3379)
# Decompiled from: Python 3.6.8 |Anaconda custom (64-bit)| (default, Feb 21 2019, 18:30:04) [MSC v.1916 64 bit (AMD64)]
# Embedded file name: asyncio\base_events.py
"""Base implementation of event loop.

The event loop can be broken up into a multiplexer (the part
responsible for notifying us of I/O events) and the event loop proper,
which wraps a multiplexer with functionality for scheduling callbacks,
immediately or at a given time in the future.

Whenever a public API takes a callback, subsequent positional
arguments will be passed to the callback if/when it is called.  This
avoids the proliferation of trivial lambdas implementing closures.
Keyword arguments for the callback are not supported; this is a
conscious design decision, leaving the door open for keyword arguments
to modify the meaning of the API call itself.
"""
import collections, concurrent.futures, heapq, inspect, itertools, logging, os, socket, subprocess, threading, time, traceback, sys, warnings, weakref
from . import compat
from . import coroutines
from . import events
from . import futures
from . import tasks
from .coroutines import coroutine
from .log import logger

__all__ = ["BaseEventLoop"]
_MIN_SCHEDULED_TIMER_HANDLES = 100
_MIN_CANCELLED_TIMER_HANDLES_FRACTION = 0.5
_FATAL_ERROR_IGNORE = (BrokenPipeError, ConnectionResetError, ConnectionAbortedError)


def _format_handle(handle):
    cb = handle._callback
    if isinstance(getattr(cb, "__self__", None), tasks.Task):
        return repr(cb.__self__)
    else:
        return str(handle)


def _format_pipe(fd):
    if fd == subprocess.PIPE:
        return "<pipe>"
    elif fd == subprocess.STDOUT:
        return "<stdout>"
    else:
        return repr(fd)


def _set_reuseport(sock):
    if not hasattr(socket, "SO_REUSEPORT"):
        raise ValueError("reuse_port not supported by socket module")
    else:
        try:
            sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
        except OSError:
            raise ValueError(
                "reuse_port not supported by socket module, SO_REUSEPORT defined but not implemented."
            )


def _is_stream_socket(sock):
    return sock.type & socket.SOCK_STREAM == socket.SOCK_STREAM


def _is_dgram_socket(sock):
    return sock.type & socket.SOCK_DGRAM == socket.SOCK_DGRAM


def _ipaddr_info(host, port, family, type, proto):
    if not hasattr(socket, "inet_pton"):
        return
    if proto not in {0, socket.IPPROTO_TCP, socket.IPPROTO_UDP} or host is None:
        return
    if type == socket.SOCK_STREAM:
        proto = socket.IPPROTO_TCP
    else:
        if type == socket.SOCK_DGRAM:
            proto = socket.IPPROTO_UDP
        else:
            return
        if port is None:
            port = 0
        else:
            if isinstance(port, bytes):
                pass
    if port == b"":
        port = 0
    if isinstance(port, str):
        if port == "":
            port = 0
        try:
            port = int(port)
        except (TypeError, ValueError):
            return

        if family == socket.AF_UNSPEC:
            afs = [socket.AF_INET]
            if hasattr(socket, "AF_INET6"):
                afs.append(socket.AF_INET6)
            else:
                afs = [family]
            if isinstance(host, bytes):
                host = host.decode("idna")
            if "%" in host:
                return
            for af in afs:
                try:
                    socket.inet_pton(af, host)
                    return (af, type, proto, "", (host, port))
                except OSError:
                    pass


def _ensure_resolved(address, *, family=0, type=socket.SOCK_STREAM, proto=0, flags=0):
    host, port = address[:2]
    info = _ipaddr_info(host, port, family, type, proto)
    if info is not None:
        fut = loop.create_future()
        fut.set_result([info])
        return fut
    else:
        return loop.getaddrinfo(
            host, port, family=family, type=type, proto=proto, flags=flags
        )


def _run_until_complete_cb(fut):
    exc = fut._exception
    if isinstance(exc, BaseException):
        if not isinstance(exc, Exception):
            return
        fut._loop.stop()


class Server(events.AbstractServer):
    def __init__(self, loop, sockets):
        self._loop = loop
        self.sockets = sockets
        self._active_count = 0
        self._waiters = []

    def __repr__(self):
        return "<%s sockets=%r>" % (self.__class__.__name__, self.sockets)

    def _attach(self):
        if not self.sockets is not None:
            raise AssertionError
        self._active_count += 1

    def _detach(self):
        if not self._active_count > 0:
            raise AssertionError
        self._active_count -= 1
        if self._active_count == 0:
            if self.sockets is None:
                self._wakeup()

    def close(self):
        sockets = self.sockets
        if sockets is None:
            return
        self.sockets = None
        for sock in sockets:
            self._loop._stop_serving(sock)

        if self._active_count == 0:
            self._wakeup()

    def _wakeup(self):
        waiters = self._waiters
        self._waiters = None
        for waiter in waiters:
            if not waiter.done():
                waiter.set_result(waiter)

    @coroutine
    def wait_closed(self):
        if self.sockets is None or self._waiters is None:
            return
        waiter = self._loop.create_future()
        self._waiters.append(waiter)
        yield from waiter


class BaseEventLoop(events.AbstractEventLoop):
    def __init__(self):
        self._timer_cancelled_count = 0
        self._closed = False
        self._stopping = False
        self._ready = collections.deque()
        self._scheduled = []
        self._default_executor = None
        self._internal_fds = 0
        self._thread_id = None
        self._clock_resolution = time.get_clock_info("monotonic").resolution
        self._exception_handler = None
        self.set_debug(
            not sys.flags.ignore_environment
            and bool(os.environ.get("PYTHONASYNCIODEBUG"))
        )
        self.slow_callback_duration = 0.1
        self._current_handle = None
        self._task_factory = None
        self._coroutine_wrapper_set = False
        if hasattr(sys, "get_asyncgen_hooks"):
            self._asyncgens = weakref.WeakSet()
        else:
            self._asyncgens = None
        self._asyncgens_shutdown_called = False

    def __repr__(self):
        return "<%s running=%s closed=%s debug=%s>" % (
            self.__class__.__name__,
            self.is_running(),
            self.is_closed(),
            self.get_debug(),
        )

    def create_future(self):
        """Create a Future object attached to the loop."""
        return futures.Future(loop=self)

    def create_task(self, coro):
        """Schedule a coroutine object.
        
        Return a task object.
        """
        self._check_closed()
        if self._task_factory is None:
            task = tasks.Task(coro, loop=self)
            if task._source_traceback:
                del task._source_traceback[-1]
            else:
                task = self._task_factory(self, coro)
            return task

    def set_task_factory(self, factory):
        """Set a task factory that will be used by loop.create_task().
        
        If factory is None the default task factory will be set.
        
        If factory is a callable, it should have a signature matching
        '(loop, coro)', where 'loop' will be a reference to the active
        event loop, 'coro' will be a coroutine object.  The callable
        must return a Future.
        """
        if factory is not None:
            if not callable(factory):
                raise TypeError("task factory must be a callable or None")
        self._task_factory = factory

    def get_task_factory(self):
        """Return a task factory, or None if the default one is in use."""
        return self._task_factory

    def _make_socket_transport(
        self, sock, protocol, waiter=None, *, extra=None, server=None
    ):
        """Create socket transport."""
        raise NotImplementedError

    def _make_ssl_transport(
        self,
        rawsock,
        protocol,
        sslcontext,
        waiter=None,
        *,
        server_side=False,
        server_hostname=None,
        extra=None,
        server=None
    ):
        """Create SSL transport."""
        raise NotImplementedError

    def _make_datagram_transport(
        self, sock, protocol, address=None, waiter=None, extra=None
    ):
        """Create datagram transport."""
        raise NotImplementedError

    def _make_read_pipe_transport(self, pipe, protocol, waiter=None, extra=None):
        """Create read pipe transport."""
        raise NotImplementedError

    def _make_write_pipe_transport(self, pipe, protocol, waiter=None, extra=None):
        """Create write pipe transport."""
        raise NotImplementedError

    @coroutine
    def _make_subprocess_transport(
        self,
        protocol,
        args,
        shell,
        stdin,
        stdout,
        stderr,
        bufsize,
        extra=None,
        **kwargs
    ):
        """Create subprocess transport."""
        raise NotImplementedError

    def _write_to_self(self):
        """Write a byte to self-pipe, to wake up the event loop.
        
        This may be called from a different thread.
        
        The subclass is responsible for implementing the self-pipe.
        """
        raise NotImplementedError

    def _process_events(self, event_list):
        """Process selector events."""
        raise NotImplementedError

    def _check_closed(self):
        if self._closed:
            raise RuntimeError("Event loop is closed")

    def _asyncgen_finalizer_hook(self, agen):
        self._asyncgens.discard(agen)
        if not self.is_closed():
            self.create_task(agen.aclose())
            self._write_to_self()

    def _asyncgen_firstiter_hook(self, agen):
        if self._asyncgens_shutdown_called:
            warnings.warn(
                (
                    "asynchronous generator {!r} was scheduled after loop.shutdown_asyncgens() call"
                ).format(agen),
                ResourceWarning,
                source=self,
            )
        self._asyncgens.add(agen)

    @coroutine
    def shutdown_asyncgens(self):
        """Shutdown all active asynchronous generators."""
        self._asyncgens_shutdown_called = True
        if self._asyncgens is None or not len(self._asyncgens):
            return
        closing_agens = list(self._asyncgens)
        self._asyncgens.clear()
        shutdown_coro = tasks.gather(
            *[ag.aclose() for ag in closing_agens], return_exceptions=True, loop=self
        )
        results = yield from shutdown_coro
        for result, agen in zip(results, closing_agens):
            if isinstance(result, Exception):
                self.call_exception_handler(
                    {
                        "message": (
                            "an error occurred during closing of asynchronous generator {!r}"
                        ).format(agen),
                        "exception": result,
                        "asyncgen": agen,
                    }
                )

    def run_forever(self):
        """Run until stop() is called."""
        self._check_closed()
        if self.is_running():
            raise RuntimeError("This event loop is already running")
        if events._get_running_loop() is not None:
            raise RuntimeError(
                "Cannot run the event loop while another loop is running"
            )
        self._set_coroutine_wrapper(self._debug)
        self._thread_id = threading.get_ident()
        if self._asyncgens is not None:
            old_agen_hooks = sys.get_asyncgen_hooks()
            sys.set_asyncgen_hooks(
                firstiter=self._asyncgen_firstiter_hook,
                finalizer=self._asyncgen_finalizer_hook,
            )
        try:
            events._set_running_loop(self)
            while 1:
                self._run_once()
                if self._stopping:
                    break

        finally:
            self._stopping = False
            self._thread_id = None
            events._set_running_loop(None)
            self._set_coroutine_wrapper(False)
            if self._asyncgens is not None:
                sys.set_asyncgen_hooks(*old_agen_hooks)

    def run_until_complete(self, future):
        """Run until the Future is done.
        
        If the argument is a coroutine, it is wrapped in a Task.
        
        WARNING: It would be disastrous to call run_until_complete()
        with the same coroutine twice -- it would wrap it in two
        different Tasks and that can't be good.
        
        Return the Future's result, or raise its exception.
        """
        self._check_closed()
        new_task = not futures.isfuture(future)
        future = tasks.ensure_future(future, loop=self)
        if new_task:
            future._log_destroy_pending = False
        future.add_done_callback(_run_until_complete_cb)
        try:
            self.run_forever()
        except:
            if new_task:
                if future.done():
                    if not future.cancelled():
                        future.exception()
            raise
        finally:
            future.remove_done_callback(_run_until_complete_cb)

        if not future.done():
            raise RuntimeError("Event loop stopped before Future completed.")
        return future.result()

    def stop(self):
        """Stop running the event loop.
        
        Every callback already scheduled will still run.  This simply informs
        run_forever to stop looping after a complete iteration.
        """
        self._stopping = True

    def close(self):
        """Close the event loop.
        
        This clears the queues and shuts down the executor,
        but does not wait for the executor to finish.
        
        The event loop must not be running.
        """
        if self.is_running():
            raise RuntimeError("Cannot close a running event loop")
        if self._closed:
            return
        if self._debug:
            logger.debug("Close %r", self)
        self._closed = True
        self._ready.clear()
        self._scheduled.clear()
        executor = self._default_executor
        if executor is not None:
            self._default_executor = None
            executor.shutdown(wait=False)

    def is_closed(self):
        """Returns True if the event loop was closed."""
        return self._closed

    if compat.PY34:

        def __del__(self):
            if not self.is_closed():
                warnings.warn(
                    "unclosed event loop %r" % self, ResourceWarning, source=self
                )
                if not self.is_running():
                    self.close()

    def is_running(self):
        """Returns True if the event loop is running."""
        return self._thread_id is not None

    def time(self):
        """Return the time according to the event loop's clock.
        
        This is a float expressed in seconds since an epoch, but the
        epoch, precision, accuracy and drift are unspecified and may
        differ per event loop.
        """
        return time.monotonic()

    def call_later(self, delay, callback, *args):
        """Arrange for a callback to be called at a given time.
        
        Return a Handle: an opaque object with a cancel() method that
        can be used to cancel the call.
        
        The delay can be an int or float, expressed in seconds.  It is
        always relative to the current time.
        
        Each callback will be called exactly once.  If two callbacks
        are scheduled for exactly the same time, it undefined which
        will be called first.
        
        Any positional arguments after the callback will be passed to
        the callback when it is called.
        """
        timer = self.call_at(self.time() + delay, callback, *args)
        if timer._source_traceback:
            del timer._source_traceback[-1]
        return timer

    def call_at(self, when, callback, *args):
        """Like call_later(), but uses an absolute time.
        
        Absolute time corresponds to the event loop's time() method.
        """
        self._check_closed()
        if self._debug:
            self._check_thread()
            self._check_callback(callback, "call_at")
        timer = events.TimerHandle(when, callback, args, self)
        if timer._source_traceback:
            del timer._source_traceback[-1]
        heapq.heappush(self._scheduled, timer)
        timer._scheduled = True
        return timer

    def call_soon(self, callback, *args):
        """Arrange for a callback to be called as soon as possible.
        
        This operates as a FIFO queue: callbacks are called in the
        order in which they are registered.  Each callback will be
        called exactly once.
        
        Any positional arguments after the callback will be passed to
        the callback when it is called.
        """
        self._check_closed()
        if self._debug:
            self._check_thread()
            self._check_callback(callback, "call_soon")
        handle = self._call_soon(callback, args)
        if handle._source_traceback:
            del handle._source_traceback[-1]
        return handle

    def _check_callback(self, callback, method):
        if coroutines.iscoroutine(callback) or coroutines.iscoroutinefunction(callback):
            raise TypeError(("coroutines cannot be used with {}()").format(method))
        if not callable(callback):
            raise TypeError(
                ("a callable object was expected by {}(), got {!r}").format(
                    method, callback
                )
            )

    def _call_soon(self, callback, args):
        handle = events.Handle(callback, args, self)
        if handle._source_traceback:
            del handle._source_traceback[-1]
        self._ready.append(handle)
        return handle

    def _check_thread(self):
        """Check that the current thread is the thread running the event loop.
        
        Non-thread-safe methods of this class make this assumption and will
        likely behave incorrectly when the assumption is violated.
        
        Should only be called when (self._debug == True).  The caller is
        responsible for checking this condition for performance reasons.
        """
        if self._thread_id is None:
            return
        thread_id = threading.get_ident()
        if thread_id != self._thread_id:
            raise RuntimeError(
                "Non-thread-safe operation invoked on an event loop other than the current one"
            )

    def call_soon_threadsafe(self, callback, *args):
        """Like call_soon(), but thread-safe."""
        self._check_closed()
        if self._debug:
            self._check_callback(callback, "call_soon_threadsafe")
        handle = self._call_soon(callback, args)
        if handle._source_traceback:
            del handle._source_traceback[-1]
        self._write_to_self()
        return handle

    def run_in_executor(self, executor, func, *args):
        self._check_closed()
        if self._debug:
            self._check_callback(func, "run_in_executor")
        if executor is None:
            executor = self._default_executor
            if executor is None:
                executor = concurrent.futures.ThreadPoolExecutor()
                self._default_executor = executor
        return futures.wrap_future(executor.submit(func, *args), loop=self)

    def set_default_executor(self, executor):
        self._default_executor = executor

    def _getaddrinfo_debug(self, host, port, family, type, proto, flags):
        msg = ["%s:%r" % (host, port)]
        if family:
            msg.append("family=%r" % family)
        if type:
            msg.append("type=%r" % type)
        if proto:
            msg.append("proto=%r" % proto)
        if flags:
            msg.append("flags=%r" % flags)
        msg = (", ").join(msg)
        logger.debug("Get address info %s", msg)
        t0 = self.time()
        addrinfo = socket.getaddrinfo(host, port, family, type, proto, flags)
        dt = self.time() - t0
        msg = "Getting address info %s took %.3f ms: %r" % (msg, dt * 1000.0, addrinfo)
        if dt >= self.slow_callback_duration:
            logger.info(msg)
        else:
            logger.debug(msg)
        return addrinfo

    def getaddrinfo(self, host, port, *, family=0, type=0, proto=0, flags=0):
        if self._debug:
            return self.run_in_executor(
                None, self._getaddrinfo_debug, host, port, family, type, proto, flags
            )
        else:
            return self.run_in_executor(
                None, socket.getaddrinfo, host, port, family, type, proto, flags
            )

    def getnameinfo(self, sockaddr, flags=0):
        return self.run_in_executor(None, socket.getnameinfo, sockaddr, flags)

    @coroutine
    def create_connection(
        self,
        protocol_factory,
        host=None,
        port=None,
        *,
        ssl=None,
        family=0,
        proto=0,
        flags=0,
        sock=None,
        local_addr=None,
        server_hostname=None
    ):
        """Connect to a TCP server.
        
        Create a streaming transport connection to a given Internet host and
        port: socket family AF_INET or socket.AF_INET6 depending on host (or
        family if specified), socket type SOCK_STREAM. protocol_factory must be
        a callable returning a protocol instance.
        
        This method is a coroutine which will try to establish the connection
        in the background.  When successful, the coroutine returns a
        (transport, protocol) pair.
        """
        if server_hostname is not None:
            if not ssl:
                raise ValueError("server_hostname is only meaningful with ssl")
        if server_hostname is None:
            if ssl:
                if not host:
                    raise ValueError(
                        "You must set server_hostname when using ssl without a host"
                    )
                server_hostname = host
        if host is not None or port is not None:
            if sock is not None:
                raise ValueError(
                    "host/port and sock can not be specified at the same time"
                )
            f1 = _ensure_resolved(
                (host, port),
                family=family,
                type=socket.SOCK_STREAM,
                proto=proto,
                flags=flags,
                loop=self,
            )
            fs = [f1]
            if local_addr is not None:
                f2 = _ensure_resolved(
                    local_addr,
                    family=family,
                    type=socket.SOCK_STREAM,
                    proto=proto,
                    flags=flags,
                    loop=self,
                )
                fs.append(f2)
            else:
                f2 = None
            yield from tasks.wait(fs, loop=self)
            infos = f1.result()
            if not infos:
                raise OSError("getaddrinfo() returned empty list")
            if f2 is not None:
                laddr_infos = f2.result()
                if not laddr_infos:
                    raise OSError("getaddrinfo() returned empty list")
            exceptions = []
            for family, type, proto, cname, address in infos:
                try:
                    sock = socket.socket(family=family, type=type, proto=proto)
                    sock.setblocking(False)
                    if f2 is not None:
                        for _, _, _, _, laddr in laddr_infos:
                            try:
                                sock.bind(laddr)
                                break
                            except OSError as exc:
                                exc = OSError(
                                    exc.errno,
                                    (
                                        "error while attempting to bind on address {!r}: {}"
                                    ).format(laddr, exc.strerror.lower()),
                                )
                                exceptions.append(exc)

                        else:
                            sock.close()
                            sock = None
                            continue

                    if self._debug:
                        logger.debug("connect %r to %r", sock, address)
                    yield from self.sock_connect(sock, address)
                except OSError as exc:
                    if sock is not None:
                        sock.close()
                    exceptions.append(exc)
                except:
                    if sock is not None:
                        sock.close()
                    raise

                break
            else:
                if len(exceptions) == 1:
                    raise exceptions[0]
                else:
                    model = str(exceptions[0])
                    if all((str(exc) == model for exc in exceptions)):
                        raise exceptions[0]
                    raise OSError(
                        ("Multiple exceptions: {}").format(
                            (", ").join((str(exc) for exc in exceptions))
                        )
                    )

        else:
            if sock is None:
                raise ValueError(
                    "host and port was not specified and no sock specified"
                )
            if not _is_stream_socket(sock):
                raise ValueError(
                    ("A Stream Socket was expected, got {!r}").format(sock)
                )
        transport, protocol = yield from self._create_connection_transport(
            sock, protocol_factory, ssl, server_hostname
        )
        if self._debug:
            sock = transport.get_extra_info("socket")
            logger.debug(
                "%r connected to %s:%r: (%r, %r)", sock, host, port, transport, protocol
            )
        return (transport, protocol)

    @coroutine
    def _create_connection_transport(
        self, sock, protocol_factory, ssl, server_hostname, server_side=False
    ):
        sock.setblocking(False)
        protocol = protocol_factory()
        waiter = self.create_future()
        if ssl:
            sslcontext = None if isinstance(ssl, bool) else ssl
            transport = self._make_ssl_transport(
                sock,
                protocol,
                sslcontext,
                waiter,
                server_side=server_side,
                server_hostname=server_hostname,
            )
        else:
            transport = self._make_socket_transport(sock, protocol, waiter)
        try:
            yield from waiter
        except:
            transport.close()
            raise

        return (transport, protocol)

    @coroutine
    def create_datagram_endpoint(
        self,
        protocol_factory,
        local_addr=None,
        remote_addr=None,
        *,
        family=0,
        proto=0,
        flags=0,
        reuse_address=None,
        reuse_port=None,
        allow_broadcast=None,
        sock=None
    ):
        """Create datagram connection."""
        if sock is not None:
            if not _is_dgram_socket(sock):
                raise ValueError(("A UDP Socket was expected, got {!r}").format(sock))
            if (
                local_addr
                or remote_addr
                or family
                or proto
                or flags
                or reuse_address
                or reuse_port
                or allow_broadcast
            ):
                opts = dict(
                    local_addr=local_addr,
                    remote_addr=remote_addr,
                    family=family,
                    proto=proto,
                    flags=flags,
                    reuse_address=reuse_address,
                    reuse_port=reuse_port,
                    allow_broadcast=allow_broadcast,
                )
                problems = (", ").join(
                    (("{}={}").format(k, v) for k, v in opts.items() if v)
                )
                raise ValueError(
                    (
                        "socket modifier keyword arguments can not be used when sock is specified. ({})"
                    ).format(problems)
                )
            sock.setblocking(False)
            r_addr = None
        else:
            if not (local_addr or remote_addr):
                if family == 0:
                    raise ValueError("unexpected address family")
                addr_pairs_info = (((family, proto), (None, None)),)
            else:
                addr_infos = collections.OrderedDict()
                for idx, addr in ((0, local_addr), (1, remote_addr)):
                    if addr is not None:
                        if not (isinstance(addr, tuple) and len(addr) == 2):
                            raise AssertionError("2-tuple is expected")
                        infos = yield from _ensure_resolved(
                            addr,
                            family=family,
                            type=socket.SOCK_DGRAM,
                            proto=proto,
                            flags=flags,
                            loop=self,
                        )
                        if not infos:
                            raise OSError("getaddrinfo() returned empty list")
                        for fam, _, pro, _, address in infos:
                            key = (fam, pro)
                            if key not in addr_infos:
                                addr_infos[key] = [None, None]
                            addr_infos[key][idx] = address

                addr_pairs_info = [
                    (key, addr_pair)
                    for key, addr_pair in addr_infos.items()
                    if not (
                        local_addr
                        and addr_pair[0] is None
                        or remote_addr
                        and addr_pair[1] is None
                    )
                ]
                if not addr_pairs_info:
                    raise ValueError("can not get address information")
            exceptions = []
            if reuse_address is None:
                reuse_address = os.name == "posix" and sys.platform != "cygwin"
            for (family, proto), (local_address, remote_address) in addr_pairs_info:
                sock = None
                r_addr = None
                try:
                    sock = socket.socket(
                        family=family, type=socket.SOCK_DGRAM, proto=proto
                    )
                    if reuse_address:
                        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
                    if reuse_port:
                        _set_reuseport(sock)
                    if allow_broadcast:
                        sock.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
                    sock.setblocking(False)
                    if local_addr:
                        sock.bind(local_address)
                    if remote_addr:
                        yield from self.sock_connect(sock, remote_address)
                        r_addr = remote_address
                except OSError as exc:
                    if sock is not None:
                        sock.close()
                    exceptions.append(exc)
                except:
                    if sock is not None:
                        sock.close()
                    raise
                else:
                    break

            else:
                raise exceptions[0]

        protocol = protocol_factory()
        waiter = self.create_future()
        transport = self._make_datagram_transport(sock, protocol, r_addr, waiter)
        if self._debug:
            if local_addr:
                logger.info(
                    "Datagram endpoint local_addr=%r remote_addr=%r created: (%r, %r)",
                    local_addr,
                    remote_addr,
                    transport,
                    protocol,
                )
            else:
                logger.debug(
                    "Datagram endpoint remote_addr=%r created: (%r, %r)",
                    remote_addr,
                    transport,
                    protocol,
                )
            try:
                yield from waiter
            except:
                transport.close()
                raise

            return (transport, protocol)

    @coroutine
    def _create_server_getaddrinfo(self, host, port, family, flags):
        infos = yield from _ensure_resolved(
            (host, port), family=family, type=socket.SOCK_STREAM, flags=flags, loop=self
        )
        if not infos:
            raise OSError(("getaddrinfo({!r}) returned empty list").format(host))
        return infos

    @coroutine
    def create_server(
        self,
        protocol_factory,
        host=None,
        port=None,
        *,
        family=socket.AF_UNSPEC,
        flags=socket.AI_PASSIVE,
        sock=None,
        backlog=100,
        ssl=None,
        reuse_address=None,
        reuse_port=None
    ):
        """Create a TCP server.
        
        The host parameter can be a string, in that case the TCP server is bound
        to host and port.
        
        The host parameter can also be a sequence of strings and in that case
        the TCP server is bound to all hosts of the sequence. If a host
        appears multiple times (possibly indirectly e.g. when hostnames
        resolve to the same IP address), the server is only bound once to that
        host.
        
        Return a Server object which can be used to stop the service.
        
        This method is a coroutine.
        """
        if isinstance(ssl, bool):
            raise TypeError("ssl argument must be an SSLContext or None")
        if host is not None or port is not None:
            if sock is not None:
                raise ValueError(
                    "host/port and sock can not be specified at the same time"
                )
            AF_INET6 = getattr(socket, "AF_INET6", 0)
            if reuse_address is None:
                reuse_address = os.name == "posix" and sys.platform != "cygwin"
            sockets = []
            if host == "":
                hosts = [None]
            else:
                if isinstance(host, str) or not isinstance(host, collections.Iterable):
                    hosts = [host]
                else:
                    hosts = host
                fs = [
                    self._create_server_getaddrinfo(
                        host, port, family=family, flags=flags
                    )
                    for host in hosts
                ]
                infos = yield from tasks.gather(*fs, **{"loop": self})
                infos = set(itertools.chain.from_iterable(infos))
                completed = False
                try:
                    for res in infos:
                        af, socktype, proto, canonname, sa = res
                        try:
                            sock = socket.socket(af, socktype, proto)
                        except socket.error:
                            if self._debug:
                                logger.warning(
                                    "create_server() failed to create socket.socket(%r, %r, %r)",
                                    af,
                                    socktype,
                                    proto,
                                    exc_info=True,
                                )
                            continue

                        sockets.append(sock)
                        if reuse_address:
                            sock.setsockopt(
                                socket.SOL_SOCKET, socket.SO_REUSEADDR, True
                            )
                        if reuse_port:
                            _set_reuseport(sock)
                        if af == AF_INET6:
                            if hasattr(socket, "IPPROTO_IPV6"):
                                sock.setsockopt(
                                    socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, True
                                )
                        try:
                            sock.bind(sa)
                        except OSError as err:
                            raise OSError(
                                err.errno,
                                "error while attempting to bind on address %r: %s"
                                % (sa, err.strerror.lower()),
                            )

                    completed = True
                finally:
                    if not completed:
                        for sock in sockets:
                            sock.close()

        else:
            if sock is None:
                raise ValueError("Neither host/port nor sock were specified")
            if not _is_stream_socket(sock):
                raise ValueError(
                    ("A Stream Socket was expected, got {!r}").format(sock)
                )
            sockets = [sock]
        server = Server(self, sockets)
        for sock in sockets:
            sock.listen(backlog)
            sock.setblocking(False)
            self._start_serving(protocol_factory, sock, ssl, server, backlog)

        if self._debug:
            logger.info("%r is serving", server)
        return server

    @coroutine
    def connect_accepted_socket(self, protocol_factory, sock, *, ssl=None):
        """Handle an accepted connection.
        
        This is used by servers that accept connections outside of
        asyncio but that use asyncio to handle connections.
        
        This method is a coroutine.  When completed, the coroutine
        returns a (transport, protocol) pair.
        """
        if not _is_stream_socket(sock):
            raise ValueError(("A Stream Socket was expected, got {!r}").format(sock))
        transport, protocol = yield from self._create_connection_transport(
            sock, protocol_factory, ssl, "", server_side=True
        )
        if self._debug:
            sock = transport.get_extra_info("socket")
            logger.debug("%r handled: (%r, %r)", sock, transport, protocol)
        return (transport, protocol)

    @coroutine
    def connect_read_pipe(self, protocol_factory, pipe):
        protocol = protocol_factory()
        waiter = self.create_future()
        transport = self._make_read_pipe_transport(pipe, protocol, waiter)
        try:
            yield from waiter
        except:
            transport.close()
            raise

        if self._debug:
            logger.debug(
                "Read pipe %r connected: (%r, %r)", pipe.fileno(), transport, protocol
            )
        return (transport, protocol)

    @coroutine
    def connect_write_pipe(self, protocol_factory, pipe):
        protocol = protocol_factory()
        waiter = self.create_future()
        transport = self._make_write_pipe_transport(pipe, protocol, waiter)
        try:
            yield from waiter
        except:
            transport.close()
            raise

        if self._debug:
            logger.debug(
                "Write pipe %r connected: (%r, %r)", pipe.fileno(), transport, protocol
            )
        return (transport, protocol)

    def _log_subprocess(self, msg, stdin, stdout, stderr):
        info = [msg]
        if stdin is not None:
            info.append("stdin=%s" % _format_pipe(stdin))
        if stdout is not None:
            if stderr == subprocess.STDOUT:
                info.append("stdout=stderr=%s" % _format_pipe(stdout))
            if stdout is not None:
                info.append("stdout=%s" % _format_pipe(stdout))
            if stderr is not None:
                info.append("stderr=%s" % _format_pipe(stderr))
        logger.debug((" ").join(info))

    @coroutine
    def subprocess_shell(
        self,
        protocol_factory,
        cmd,
        *,
        stdin=subprocess.PIPE,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        universal_newlines=False,
        shell=True,
        bufsize=0 ** kwargs
    ):
        if not isinstance(cmd, (bytes, str)):
            raise ValueError("cmd must be a string")
        if universal_newlines:
            raise ValueError("universal_newlines must be False")
        if not shell:
            raise ValueError("shell must be True")
        if bufsize != 0:
            raise ValueError("bufsize must be 0")
        protocol = protocol_factory()
        if self._debug:
            debug_log = "run shell command %r" % cmd
            self._log_subprocess(debug_log, stdin, stdout, stderr)
        transport = yield from self._make_subprocess_transport(
            protocol, cmd, True, stdin, stdout, stderr, bufsize, **kwargs
        )
        if self._debug:
            logger.info("%s: %r", debug_log, transport)
        return (transport, protocol)

    @coroutine
    def subprocess_exec(
        self,
        protocol_factory,
        program,
        *args,
        stdin=subprocess.PIPE,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        universal_newlines=False,
        shell=False,
        bufsize=0 ** kwargs
    ):
        if universal_newlines:
            raise ValueError("universal_newlines must be False")
        if shell:
            raise ValueError("shell must be False")
        if bufsize != 0:
            raise ValueError("bufsize must be 0")
        popen_args = (program,) + args
        for arg in popen_args:
            if not isinstance(arg, (str, bytes)):
                raise TypeError(
                    "program arguments must be a bytes or text string, not %s"
                    % type(arg).__name__
                )

        protocol = protocol_factory()
        if self._debug:
            debug_log = "execute program %r" % program
            self._log_subprocess(debug_log, stdin, stdout, stderr)
        transport = yield from self._make_subprocess_transport(
            protocol, popen_args, False, stdin, stdout, stderr, bufsize, **kwargs
        )
        if self._debug:
            logger.info("%s: %r", debug_log, transport)
        return (transport, protocol)

    def get_exception_handler(self):
        """Return an exception handler, or None if the default one is in use.
        """
        return self._exception_handler

    def set_exception_handler(self, handler):
        """Set handler as the new event loop exception handler.
        
        If handler is None, the default exception handler will
        be set.
        
        If handler is a callable object, it should have a
        signature matching '(loop, context)', where 'loop'
        will be a reference to the active event loop, 'context'
        will be a dict object (see `call_exception_handler()`
        documentation for details about context).
        """
        if handler is not None:
            if not callable(handler):
                raise TypeError(
                    ("A callable object or None is expected, got {!r}").format(handler)
                )
        self._exception_handler = handler

    def default_exception_handler(self, context):
        """Default exception handler.
        
        This is called when an exception occurs and no exception
        handler is set, and can be called by a custom exception
        handler that wants to defer to the default behavior.
        
        This default handler logs the error message and other
        context-dependent information.  In debug mode, a truncated
        stack trace is also appended showing where the given object
        (e.g. a handle or future or task) was created, if any.
        
        The context parameter has the same meaning as in
        `call_exception_handler()`.
        """
        message = context.get("message")
        if not message:
            message = "Unhandled exception in event loop"
        exception = context.get("exception")
        if exception is not None:
            exc_info = (type(exception), exception, exception.__traceback__)
        else:
            exc_info = False
        if "source_traceback" not in context:
            if self._current_handle is not None:
                if self._current_handle._source_traceback:
                    context["handle_traceback"] = self._current_handle._source_traceback
        log_lines = [message]
        for key in sorted(context):
            if key in frozenset({"exception", "message"}):
                continue
            value = context[key]
            if key == "source_traceback":
                tb = ("").join(traceback.format_list(value))
                value = "Object created at (most recent call last):\n"
                value += tb.rstrip()
            else:
                if key == "handle_traceback":
                    tb = ("").join(traceback.format_list(value))
                    value = "Handle created at (most recent call last):\n"
                    value += tb.rstrip()
                else:
                    value = repr(value)
                log_lines.append(("{}: {}").format(key, value))

        logger.error(("\n").join(log_lines), exc_info=exc_info)

    def call_exception_handler(self, context):
        """Call the current event loop's exception handler.
        
        The context argument is a dict containing the following keys:
        
        - 'message': Error message;
        - 'exception' (optional): Exception object;
        - 'future' (optional): Future instance;
        - 'handle' (optional): Handle instance;
        - 'protocol' (optional): Protocol instance;
        - 'transport' (optional): Transport instance;
        - 'socket' (optional): Socket instance;
        - 'asyncgen' (optional): Asynchronous generator that caused
                                 the exception.
        
        New keys maybe introduced in the future.
        
        Note: do not overload this method in an event loop subclass.
        For custom exception handling, use the
        `set_exception_handler()` method.
        """
        if self._exception_handler is None:
            try:
                self.default_exception_handler(context)
            except Exception:
                logger.error("Exception in default exception handler", exc_info=True)

        try:
            self._exception_handler(self, context)
        except Exception as exc:
            try:
                self.default_exception_handler(
                    {
                        "message": "Unhandled error in exception handler",
                        "exception": exc,
                        "context": context,
                    }
                )
            except Exception:
                logger.error(
                    "Exception in default exception handler while handling an unexpected error in custom exception handler",
                    exc_info=True,
                )

    def _add_callback(self, handle):
        """Add a Handle to _scheduled (TimerHandle) or _ready."""
        if not isinstance(handle, events.Handle):
            raise AssertionError("A Handle is required here")
        if handle._cancelled:
            return
        if not not isinstance(handle, events.TimerHandle):
            raise AssertionError
        self._ready.append(handle)

    def _add_callback_signalsafe(self, handle):
        """Like _add_callback() but called from a signal handler."""
        self._add_callback(handle)
        self._write_to_self()

    def _timer_handle_cancelled(self, handle):
        """Notification that a TimerHandle has been cancelled."""
        if handle._scheduled:
            self._timer_cancelled_count += 1

    def _run_once(self):
        """Run one full iteration of the event loop.
        
        This calls all currently ready callbacks, polls for I/O,
        schedules the resulting callbacks, and finally schedules
        'call_later' callbacks.
        """
        sched_count = len(self._scheduled)
        if sched_count > _MIN_SCHEDULED_TIMER_HANDLES:
            if (
                self._timer_cancelled_count / sched_count
                > _MIN_CANCELLED_TIMER_HANDLES_FRACTION
            ):
                new_scheduled = []
                for handle in self._scheduled:
                    if handle._cancelled:
                        handle._scheduled = False
                    else:
                        new_scheduled.append(handle)

                heapq.heapify(new_scheduled)
                self._scheduled = new_scheduled
                self._timer_cancelled_count = 0
            while self._scheduled:
                if self._scheduled[0]._cancelled:
                    self._timer_cancelled_count -= 1
                    handle = heapq.heappop(self._scheduled)
                    handle._scheduled = False

        timeout = None
        if self._ready or self._stopping:
            timeout = 0
        else:
            if self._scheduled:
                when = self._scheduled[0]._when
                timeout = max(0, when - self.time())
        if self._debug and timeout != 0:
            t0 = self.time()
            event_list = self._selector.select(timeout)
            dt = self.time() - t0
            if dt >= 1.0:
                level = logging.INFO
            else:
                level = logging.DEBUG
            nevent = len(event_list)
            if timeout is None:
                logger.log(level, "poll took %.3f ms: %s events", dt * 1000.0, nevent)
            else:
                if nevent:
                    logger.log(
                        level,
                        "poll %.3f ms took %.3f ms: %s events",
                        timeout * 1000.0,
                        dt * 1000.0,
                        nevent,
                    )
                else:
                    if dt >= 1.0:
                        logger.log(
                            level,
                            "poll %.3f ms took %.3f ms: timeout",
                            timeout * 1000.0,
                            dt * 1000.0,
                        )
        else:
            event_list = self._selector.select(timeout)
        self._process_events(event_list)
        end_time = self.time() + self._clock_resolution
        while self._scheduled:
            handle = self._scheduled[0]
            if handle._when >= end_time:
                break
            handle = heapq.heappop(self._scheduled)
            handle._scheduled = False
            self._ready.append(handle)

        ntodo = len(self._ready)
        for i in range(ntodo):
            handle = self._ready.popleft()
            if handle._cancelled:
                continue
            if self._debug:
                try:
                    self._current_handle = handle
                    t0 = self.time()
                    handle._run()
                    dt = self.time() - t0
                    if dt >= self.slow_callback_duration:
                        logger.warning(
                            "Executing %s took %.3f seconds", _format_handle(handle), dt
                        )
                finally:
                    self._current_handle = None

            else:
                handle._run()

        handle = None

    def _set_coroutine_wrapper(self, enabled):
        try:
            set_wrapper = sys.set_coroutine_wrapper
            get_wrapper = sys.get_coroutine_wrapper
        except AttributeError:
            return
        else:
            enabled = bool(enabled)
            if self._coroutine_wrapper_set == enabled:
                return
            wrapper = coroutines.debug_wrapper
            current_wrapper = get_wrapper()
            if enabled:
                if current_wrapper not in (None, wrapper):
                    warnings.warn(
                        "loop.set_debug(True): cannot set debug coroutine wrapper; another wrapper is already set %r"
                        % current_wrapper,
                        RuntimeWarning,
                    )
                else:
                    set_wrapper(wrapper)
                    self._coroutine_wrapper_set = True
            else:
                if current_wrapper not in (None, wrapper):
                    warnings.warn(
                        "loop.set_debug(False): cannot unset debug coroutine wrapper; another wrapper was set %r"
                        % current_wrapper,
                        RuntimeWarning,
                    )
                else:
                    set_wrapper(None)
                    self._coroutine_wrapper_set = False

    def get_debug(self):
        return self._debug

    def set_debug(self, enabled):
        self._debug = enabled
        if self.is_running():
            self._set_coroutine_wrapper(enabled)
